U.S. Pat. No. 6,389,693 describes a manufacturing method comprising a step for measuring the diameter of the gas purification unit, a step for measuring the mass of the support element, and a step for calculating the diameter of the enclosure as a function of the measurements done.
In certain purification members obtained using this method, the exhaust gas purification unit is not completely supported inside the enclosure.
In this context, the invention aims to propose a manufacturing method that is even more precise.